RESUMEN
Introduction: Land Surface Temperature (LST) is a significant climatic variable and defined as how hot the "surface" of the Earth would feel to the physical touch in a particular location. A spatial analysis of the land surface temperature with respect to different land use/cover changes is vital to evaluate the hydrological processes. Methods: The objective of this paper is to assess the spatial variation of land surface temperature derived from thermal bands of the Landsat 8 Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS) by using split window algorithm. Place and Data: The study was conducted in Lalgudi block of Trichy District, Tamil Nadu, India. The block has diverse environment like forest area, barren land, river sand bed, water bodies, dry vegetation, cultivated areas (paddy, sugarcane, banana etc.) and settlements. Landsat 8 satellite images for four selected scenes (December 2014 & January 2015 and December 2017 & January 2018) were used to estimate the LST. Results: The spatial and temporal variation of Normalized Difference Vegetation Index (NDVI) and LST were estimated. The average NDVI values of cropped fields varied from 0.3 to 0.5 in all the scenes. The maximum value of LST ranging from 35 to 40°C was recorded in river sand bed. Subsequently, semi-urban settlements in the central part of Lalgudi block exhibited higher temperature ranging from 28 – 30°C. The LST of paddy crop and sugarcane was in the range of 23 to 25°C. The water bodies exhibited LST around 20°C. The coconut plantations, forest area and Prosopis juliflora showed LST value ranging from 24 – 29°C. This kind of block level monitoring studies helps in adopting suitable policies to overcome or minimize the problems triggered by increase in land surface temperature.
RESUMEN
Aims: To estimate incidences of malaria infection in an urban setting using Remotely sensed data and matching same with hospital records to validate the use of Remote sensing data as a methodology for studying the prevalence of malaria. Study Design: Analyses of 2006 Nigeriasat-1 and Land sat ETM+satellite data for modeling malaria infection. Place and Duration of Study: Lokoja, Capital city of Kogi State in Central Nigeria, between March 2012 and January 2013. Methodology: Extraction of land use types, NDVI and LST maps using ILWIS 3.3 and Idrisi software. Cross tabulation of extracted maps to carry out correlational analyses while buffer analysis was conducted to ascertain risk zones of malaria infection in the town. The clinical data was used in determining the recorded incidence of malaria in the study area. Results: Built-up area, sand bars and vacant land occupy least land cover (i.e. 28.31%) while urban agricultural land, vegetation and water bodies covered 344.33km2 (59.72%), 41.98km2 (7.28%) and 18.51km2 (3.21%), respectively. The LSE value ranges from 0.92 to 0.989 with an average of 0.955 whereas the highest emissivity is recorded where vegetation is very dense and the lowest recorded for Sand bars. The LST for sand bars, vacant land and built-up area recorded the highest average temperatures of 41.13°C, 35.66°C and 34.56°C, respectively. The highest negative correlation was found in vegetation (-0.96) with other negative values recorded for urban agricultural land and water bodies. The lowest correlation (0.65) was recorded from areas covered with sand bars. The UHI map shows that temperatures at the periphery are lower (about 18°C) but higher at the core (from 26°C to 40°C). Conclusion: The interplay of NDVI, LST and land use/cover types of Lokoja provides the impetus for the rising incidence of malaria in Lokoja town. Proper urban planning which will support sufficient drainages, effective waste removal, sanitary landfill sites, vegetation control, fumigation, etc. can boost sanitary conditions whilst minimizing the availability of breeding sites for mosquito larvae. At the household levels, extensive use of bed nets and periodic fumigation appear to be the most appropriate short-term measures for curtailing the incidences of malaria at the study area.